Joker (Arkham Asylum)

Joker is the nemesis of Batman. A chemical accident earlier in his life changed his visual appearance and caused him to go crazy. Joker tends to have a very dark sense of humor and it reflects in the crimes he commits. Unlike most of the other criminals Batman faces, Joker seems to completely lack a motive for the crimes he commits, he just loves anarchy and chaos. He is playable for a brief period in Arkham Asylum.